Cysteine biosynthesis in higher plants: a new member of the Arabidopsis thaliana serine acetyltransferase small gene-family obtained by functional complementation of an Escherichia coli cysteine auxotroph

A cDNA clone, Sat-52, encoding a novel isoform of serine acetyltransferase (EC 2.3.1.30) was isolated by functional complementation of an Escherichia coli cysE mutant defective in serine acetyltransferase. The 1158 base pair clone contains a full-length open reading frame encoding a deduced protein of 312 amino acids with an M(r) of 32.77 kDa. Northern analysis revealed a single transcript of ca 1.19 kb that did not increase in abundance under sulfate limitation. Genomic Southern hybridization suggests the presence of a single copy of the Sat-52 gene.